ULPC FeMn has been conventionally produced by charging a Mn-containing melt made of low P ore used as a material for minimizing P content and a reducing agent, for example, Si or FeSi, and mixing and stirring charged materials through horizontal eccentric movement, thereby reducing Mn oxide of the Mn-containing melt with the reducing agent, yielding high-quality and high-purity FeMn. However, the low P ore or the non-carbonaceous reducing agent (Si or FeSi) is expensive, undesirably increasing the production cost of ULPC FeMn. In order to achieve an efficient reaction in the process, a high-purity reducing agent in which Si component of the non-carbonaceous reducing agent is 65˜98 wt % must be used. If the purity of Si component is not high, upon the desilication reaction through mixing and stirring with the Mn-containing melt, Mn recovery is low, thus making it difficult to ensure the economic benefits of the process. Further, slag produced after the process is not recycled but is discarded, undesirably incurring resource waste problems.